Portable or hand held vehicle battery jump starting apparatus with battery cell equalization circuit

ABSTRACT

A hand held, portable jump starter device includes a multi-cell rechargeable battery with at least three battery cells connected in series, and a battery cell equalization circuit connected to the multi-cell rechargeable battery in parallel with the battery charge controller, wherein the battery cell equalization circuit includes an individual battery cell equalization circuit for each of the at least three battery cells, and wherein each of the individual battery cell equalization circuits is configured to discharge a particular battery cell upon the particular battery cell reaching a cell voltage exceeding a pre-determined upper voltage threshold until the particular battery cell reaches a pre-determined lower voltage level below the upper voltage threshold, and wherein the individual battery cell equalization circuits are configured to charge lower voltage individual battery cells at a higher rate allowing lower voltage individual battery cells to catch up in voltage to an individual battery cell having a highest voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 17/166,465,filed on Feb. 3, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/587,624, filed on Sep. 30, 2019, which was acontinuation of U.S. patent application Ser. No. 16/461,562, filed onMay 16, 2019, which was a 371 of International ApplicationPCT/US2018/050243, filed on Sep. 10, 2018, which is acontinuation-in-part of International Application No.:PCT/US2018/025424, filed on Mar. 30, 2018, which claims benefit ofpriority to U.S. Provisional Application No. 62/480,082, filed on Mar.31, 2017, each of which are hereby incorporated by reference herein intheir entirety.

FIELD

The present invention relates generally to an electronic device orapparatus having multiple batteries or a battery pack having multiplebattery cells provided with a battery cell equalization circuit. Forexample, the apparatus is a portable vehicle battery jump startingapparatus for jump starting a vehicle having a depleted or dischargedbattery. The portable vehicle battery jump starting device comprises abattery pack having multiple individual battery cells and a battery cellequalization circuit.

BACKGROUND

Prior art devices are known, which provide either a pair of electricalconnector cables that connect a fully-charged battery of another vehicleto the engine start circuit of the dead battery vehicle, or portablebooster devices which include a fully-charged battery which can beconnected in circuit with the vehicle's engine starter through a pair ofcables.

Problems with the prior art apparatus arose when either the jumperterminals or clamps of the cables were inadvertently brought intocontact with each other while the other ends were connected to or beingpower, or when the positive and negative jumper terminals or clamps wereconnected to the opposite polarity terminals in the vehicle to bejumped, thereby causing a short circuit resulting in sparking andpotential damage to batteries and/or bodily injury. Various attempts toeliminate these problems have been made in the prior art.

U.S. Pat. No. 6,212,054 issued Apr. 3, 2001, discloses a battery boosterpack that is polarity sensitive and can detect proper and improperconnections before providing a path for electric current flow. Thedevice uses a set of LEDs connected to optical couplers oriented by acontrol circuit. The control circuit controls a solenoid assemblycontrolling the path of power current. The control circuit causes powercurrent to flow through the solenoid assembly only if the points ofcontact of booster cable clamp connections have been properly made.

U.S. Pat. No. 6,632,103 issued Oct. 14, 2003, discloses an adaptivebooster cable connected with two pairs of clips, wherein the two pairsof clips are respectively attached to two batteries to transmit powerfrom one battery to the other battery. The adaptive booster cableincludes a polarity detecting unit connected to each clip, a switchingunit and a current detecting unit both provided between the two pairs ofclips. After the polarity of each clip is sensed by the polaritydetecting unit, the switching unit generates a proper connection betweenthe two batteries. Therefore, the positive and negative terminals of thetwo batteries are correctly connected based on the detected result ofthe polarity detecting unit.

U.S. Pat. No. 8,493,021 issued Jul. 23, 2013, discloses apparatus thatmonitors the voltage of the battery of a vehicle to be jump started andthe current delivered by the jump starter batteries to determine if aproper connection has been established and to provide fault monitoring.

Only if the proper polarity is detected can the system operate. Thevoltage is monitored to determine open circuit, disconnected conductiveclamps, shunt cable fault, and solenoid fault conditions. The currentthrough the shunt cable is monitored to determine if there is a batteryexplosion risk, and for excessive current conditions presenting anoverheating condition, which may result in fire. The system includes aninternal battery to provide the power to the battery of the vehicle tobe jump started. Once the vehicle is started, the unit automaticallyelectrically disconnects from the vehicle's battery.

U.S. Pat. No. 5,189,359 issued Feb. 23, 1993, discloses a jumper cabledevice having two bridge rectifiers for developing a reference voltage,a four-input decoder for determining which terminals are to be connectedbased on a comparison of the voltage at each of the four terminals tothe reference voltage, and a pair of relays for effecting the correctconnection depending on the determination of the decoder. No connectionwill be made unless only one terminal of each battery has a highervoltage than the reference voltage, indicating “positive” terminals, andone has a lower voltage than the reference voltage, indicating“negative” terminals, and that, therefore, the two high voltageterminals may be connected and the two lower voltage terminals may beconnected. Current flows once the appropriate relay device is closed.The relay device is preferably a MOSFET combined with a series array ofphotodiodes that develop MOSFET gate-closing potential when the decoderoutput causes an LED to light.

U.S. Pat. No. 5,795,182 issued Aug. 18, 1998, discloses a polarityindependent set of battery jumper cables for jumping a first battery toa second battery. The apparatus includes a relative polarity detectorfor detecting whether two batteries are configured cross or parallel. Athree-position high current capacity crossbar pivot switch is responsiveto the relative polarity detector for automatically connecting the plusterminals of the two batteries together and the minus terminals of thetwo batteries together regardless of whether the configuration detectedis cross or parallel, and an undercurrent detector and a delay circuitfor returning the device to its ready and unconnected state after thedevice has been disconnected from one of the batteries. The crossbarpivot switch includes two pairs of contacts, and a pivot arm that pivotsabout two separate points to ensure full electrical contact between thepairs of contacts.

The present invention can also be used to produce a battery charger thatmay be connected to a battery without regard to the polarity of thebattery.

U.S. Pat. No. 6,262,492 issued Jul. 17, 2001, discloses a car batteryjumper cable for accurately coupling an effective power source to afailed or not charged battery, which includes a relay switching circuitconnected to the power source and the battery by two current conductorpairs. First and second voltage polarity recognition circuits arerespectively connected to the power source and the battery by arespective voltage conductor pair to recognize the polarity of the powersource and the battery. A logic recognition circuit produces a controlsignal subject to the polarity of the power source and the battery, anda driving circuit controlled by the control signal from the logicrecognition circuit drives the relay switching circuit, enabling the twopoles of the power source to be accurately coupled to the two poles ofthe battery.

U.S. Pat. No. 5,635,817 issued Jun. 3, 1997, discloses a vehicle batterycharging device that includes a control housing having cables includinga current limiting device to prevent exceeding of a predeterminedmaximum charging current of about 40 to 60 amps. The control housingincludes a polarity detecting device to verify the correct polarity ofthe connection of the terminals of the two batteries and to electricallydisconnect the two batteries if there is an incorrect polarity.

U.S. Pat. No. 8,199,024 issued Jun. 12, 2012, discloses a safety circuitin a low voltage connecting system that leaves the two low-voltagesystems disconnected until it determines that it is safe to make aconnection. When the safety circuit determines that no unsafe conditionsexist and that it is safe to connect the two low-voltage systems, thesafety circuit may connect the two systems by way of a “soft start” thatprovides a connection between the two systems over a period of time thatreduces or prevents inductive voltage spikes on one or more of thelow-voltage systems. When one of the low-voltage systems has acompletely-discharged battery incorporated into it, a method is used fordetection of proper polarity of the connections between the low-voltagesystems. The polarity of the discharged battery is determined by passingone or more test currents through it and determining whether acorresponding voltage rise is observed.

U.S. Pat. No. 5,793,185 issued Aug. 11, 1998, discloses a hand-held jumpstarter having control components and circuits to prevent overchargingand incorrect connection to batteries.

Further, there exists a problem with the prior art electronic devices orapparatus having multiple batteries or a battery pack with multiplebattery cells.

For example, lithium-ion (Li-ion) batteries have been known to explodeor catch fire due to overheating when individual battery cells getovercharged. The battery life also decreases, if individual batterycells are not equally charged, causing significantly unequal voltagesacross the individual battery cells.

Currently, portable or hand-held vehicle jump starters using Li-ionbatteries do not include battery equalization circuits. Thus, Li-ionbatteries can suffer from the above overcharging problems. An example ofsuch a hand-held vehicle jump starter is disclosed in U.S. Pat. No.9,007,015, which is incorporated herein by reference.

A battery cell equalization circuit according to the present inventioncan be applied or incorporated into the portable or hand-held vehiclejump starter device disclosed and claimed in U.S. Pat. No. 9,007,015.

There exists a need to provide battery equalization circuits, forexample, with electronic apparatus having multiple Li-ion batteries orLi-ion battery packs having multiple battery cells, for example, inrechargeable electronic devices such as the portable or hand-heldvehicle jump starter device according to the present invention.

While the prior art attempted to provide solutions to one or more of theabovementioned problem(s) as discussed above, each of the prior artsolutions suffers from other shortcomings, either in complexity, costand/or has potential for malfunction. Accordingly, there exists a needin the art for further improvements to electronic devices or apparatushaving multiple batteries or battery packs having multiple battery cellssuch as used in vehicle jump starting devices or apparatus.

SUMMARY

In accordance with an aspect of the invention, an electronic device orapparatus is provided for jump starting a vehicle engine, including: aninternal power supply; an output port having positive and negativepolarity outputs; a vehicle battery isolation sensor connected incircuit with the positive and negative polarity outputs, configured todetect presence of a vehicle battery connected between the positive andnegative polarity outputs; a reverse polarity sensor connected incircuit with the positive and negative polarity outputs, configured todetect polarity of a vehicle battery connected between the positive andnegative polarity outputs; a power FET switch connected between theinternal power supply and the output port; and a microcontrollerconfigured to receive input signals from the vehicle isolation sensorand the reverse polarity sensor, and to provide an output signal to thepower FET switch, such that the power FET switch is turned on to connectthe internal power supply to the output port in response to signals fromthe sensors indicating the presence of a vehicle battery at the outputport and proper polarity connection of positive and negative terminalsof the vehicle battery with the positive and negative polarity outputs.

In accordance with another aspect of the invention, the internal powersupply is a rechargeable lithium-ion (Li-ion) battery pack.

In accordance with yet another aspect of the invention, a jumper cabledevice is provided with a plug configured to plug into an output port ofa handheld battery charger booster device having an internal powersupply; a pair of cables integrated with the plug at one respective endthereof; the pair of cables being configured to be separately connectedto terminals of a battery at another respective end thereof.

The present invention also provides a battery cell equalization circuitfor an electronic device or apparatus having multiple battery cells(e.g. Li-ion batteries) or a battery pack having multiple battery cells(e.g. Li-ion battery cells). For example, the batteries or battery packcan comprise or consist of multiple batteries connected to a batterycell equalization circuit. The battery cell equalization circuit (e.g.circuit board) can be packaged internally with the batteries or batterypack, or can be an electronic circuit or component separate from thebattery pack installed in the electronic device or apparatus powered bythe battery pack (e.g. circuit board within electronic device, but notpackaged with battery pack). The batteries or battery packs can berechargeable using lithium-ion, nickel cadmium, or rechargeablebatteries or battery cells.

The battery cell equalization circuit according to the presentinvention, for example, can be applied or implemented in a rechargeableelectronic device or apparatus such as a tool, portable or hand-heldvehicle jump starter, vehicle, electrical vehicle (e.g. electric car,electric truck, electric bus, electric golf cart, electric utility cart,motorcycle, mini bike, scooter, go kart), radio, electronic player,radio controlled device, radio controlled toy (e.g. RIC airplane, RICboat, R/C car, R/C truck), game, or other numerous other rechargeableelectronic devices, apparatus, or applications.

The battery cell equalization circuit can be applied to or used in aportable or hand-held jump starter. This type of electronic deviceconveys a significant amount of energy or power from the rechargeablebatteries or battery pack to a deplete or discharged battery being jumpstarted in a short amount of time requiring the batteries or battercells to all be fully charged and balanced. The battery cellequalization circuit according to the present invention can beconfigured to be simple, safe, effective, low cost, and can include acontrollable mechanism to enable or disable itself from trying to sensethe cell voltages and trying to equalize them.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of a handheld vehicle battery boostapparatus in accordance with one aspect of the present invention;

FIGS. 2A-2C are schematic circuit diagrams of an example embodiment of ahandheld vehicle battery boost apparatus in accordance with an aspect ofthe invention;

FIG. 3 is a perspective view of a handheld jump starter booster devicein accordance with one example embodiment of the invention; and

FIG. 4 is a planar view of a jumper cable usable with the handheld jumpstarter booster device in accordance with another aspect of theinvention.

FIG. 5 is a schematic circuit diagram of a battery cell equalizationcircuit according to the present invention.

DETAILED DESCRIPTION

FIG. 1 is a functional block diagram of a handheld battery boosteraccording to one aspect of the invention. At the heart of the handheldbattery booster is a lithium polymer battery pack 32, which storessufficient energy to jump start a vehicle engine served by aconventional 12 volt lead-acid or valve regulated lead-acid battery. Inone example embodiment, a high-surge lithium polymer battery packincludes three 3.7V, 2666 mAh lithium polymer batteries in a 351 Pconfiguration. The resulting battery pack provides 11.1V, 2666 Ah (8000Ah at 3.7V, 29.6 Wh). Continuous discharge current is 25 C (or 200amps), and burst discharge current is 50 C (or 400 amps). The maximumcharging current of the battery pack is 8000 mA (8 amps).

A programmable microcontroller unit (MCU) 1 receives various inputs andproduces informational as well as control outputs. The programmable MCU1 further provides flexibility to the system by allowing updates infunctionality and system parameters, without requiring any change inhardware. According to one example embodiment, an 8 bit microcontrollerwith 2K.times.15 bits of flash memory is used to control the system. Onesuch microcontroller is the HT67F30, which is commercially availablefrom Holtek Semiconductor Inc.

A car battery reverse sensor 10 monitors the polarity of the vehiclebattery 72 when the handheld battery booster device is connected to thevehicle's electric system. As explained below, the booster deviceprevents the lithium battery pack from being connected to the vehiclebattery 72 when the terminals of the battery 72 are connected to thewrong terminals of the booster device. A car battery isolation sensor 12detects whether or not a vehicle battery 72 is connected to the boosterdevice, and prevents the lithium battery pack from being connected tothe output terminals of the booster device unless there is a good (e.g.chargeable) battery connected to the output terminals.

A smart switch FET circuit 15 electrically switches the handheld batterybooster lithium battery to the vehicle's electric system only when thevehicle battery is determined by the MCU 1 to be present (in response toa detection signal provided by isolation sensor 12) and connected withthe correct polarity (in response to a detection signal provided byreverse sensor 10). A lithium battery temperature sensor 20 monitors thetemperature of the lithium battery pack 32 to detect overheating due tohigh ambient temperature conditions and overextended current draw duringjump starting. A lithium battery voltage measurement circuit 24 monitorsthe voltage of the lithium battery pack 32 to prevent the voltagepotential from rising too high during a charging operation and fromdropping too low during a discharge operation.

Lithium-ion battery back-charge protection diodes 28 prevent any chargecurrent being delivered to the vehicle battery 72 from flowing back tothe lithium battery pack 32 from the vehicle's electrical system.Flashlight LED circuit 36 is provided to furnish a flashlight functionfor enhancing light under a vehicle's hood in dark conditions, as wellas providing SOS and strobe lighting functions for safety purposes whena vehicle may be disabled in a potentially dangerous location. Voltageregulator 42 provides regulation of internal operating voltage for themicrocontroller and sensors. On/Off manual mode and flashlight switches46 allow the user to control power-on for the handheld battery boosterdevice, to control manual override operation if the vehicle has nobattery, and to control the flashlight function. The manual buttonfunctions only when the booster device is powered on. This button allowsthe user to jump-start vehicles that have either a missing battery, orthe battery voltage is so low that automatic detection by the MCU is notpossible. When the user presses and holds the manual override button fora predetermined period time (such as three seconds) to preventinadvertent actuation of the manual mode, the internal lithium ionbattery power is switched to the vehicle battery connect port. The onlyexception to the manual override is if the car battery is connected inreverse. If the car battery is connected in reverse, the internallithium

battery power shall never be switched to the vehicle battery connectport. USB charge circuit 52 converts power from any USB charger powersource, to charge voltage and current for charging the lithium batterypack 32. USB output 56 provides a USB portable charger for chargingsmartphones, tablets, and other rechargeable electronic devices.Operation indicator LEDs 60 provide visual indication of lithium batterycapacity status as well as an indication of smart switch activationstatus (indicating that power is being provided to the vehicle'selectrical system).

Detailed operation of the handheld booster device will now be describedwith reference to the schematic diagrams of FIGS. 2A-2C. As shown inFIG. 2A, the microcontroller unit 1 is the center of all inputs andoutputs. The reverse battery sensor 10 comprises an optically coupledisolator phototransistor (4N27) connected to the terminals of vehiclebattery 72 at input pins 1 and 2 with a diode D8 in the lead conductorof pin 1 (associated with the negative terminal CB−), such that if thebattery 72 is connected to the terminals of the booster device with thecorrect polarity, the optocoupler LED 11 will not conduct current, andis therefore turned off, providing a “1” or high output signal to theMCU 1. The car battery isolation sensor 12 comprises an opticallycoupled isolator phototransistor (4N27) connected to the terminals ofvehicle battery 72 at input pins 1 and 2 with a diode D7 in the leadconductor of pin 1 (associated with the positive terminal CB+), suchthat if the battery 72 is connected to the terminals of the boosterdevice with the correct polarity, the optocoupler LED 11A will conductcurrent, and is therefore turned on, providing a “0” or low outputsignal to the MCU, indicating the presence of a battery across thejumper output terminals of the handheld booster device.

If the car battery 72 is connected to the handheld booster device withreverse polarity, the optocoupler LED 11 of the reverse sensor 10 willconduct current, providing a “0” or low signal to microcontroller unit1. Further, if no battery is connected to the hand held booster device,the optocoupler LED 11 A of the isolation sensor 12 will not conductcurrent, and is therefore turned off, providing a “1” or high outputsignal to the MCU, indicating the absence of any battery connected tothe handheld booster device. Using these specific inputs, themicrocontroller software of MCU 1 can determine when it is safe to turnon the smart switch FET 15, thereby connecting the lithium battery packto the jumper terminals of the booster device. Consequently, if the carbattery 72 either is not connected to the booster device at all, or isconnected with reverse polarity, the MCU 1 can keep the smart switch FET15 from being turned on, thus prevent sparking/short circuiting of thelithium battery pack.

As shown in FIG. 2B, the FET smart switch 15 is driven by an output ofthe microcontroller 1. The FET smart switch 15 includes three FETs (015,018, and 019) in parallel, which spreads the distribution of power fromthe lithium battery pack over the FETs. When that microcontroller outputis driven to a logic low, FETs 16 are all in a high resistance state,therefore not allowing current to flow from the internal lithium batterynegative contact 17 to the car battery 72 negative contact. When themicro controller output is driven to a logic high, the FETs 16 (015,018, and 019) are in a low resistant state, allowing current to flowfreely from the internal lithium battery pack negative contact 17 (LB−)to the car battery 72 negative contact (CB−). In this way, themicrocontroller software controls the connection of the internal lithiumbattery pack 32 to the vehicle battery 72 for jumpstarting the carengine.

Referring back to FIG. 2A, the internal lithium battery pack voltage canbe accurately measured using circuit 24 and one of the analog-to-digitalinputs of the microcontroller 1. Circuit 24 is designed to sense whenthe main 3.3V regulator 42 voltage is on, and to turn on transistor 23when the voltage of regulator 42 is on. When transistor 23 isconducting, it turns on FET 22, thereby providing positive contact (LB+)of the internal lithium battery a conductive path to voltage divider 21allowing a lower voltage range to be brought to the microcontroller tobe read. Using this input, the microcontroller software can determine ifthe lithium battery voltage is too low during discharge operation or toohigh during charge operation, and take appropriate action to preventdamage to electronic components.

Still referring to FIG. 2A, the temperature of the internal lithiumbattery pack 32 can be accurately measured by two negative temperaturecoefficient (NTC) devices 20. These are devices that reduce theirresistance when their temperature rises. The circuit is a voltagedivider that brings the result to two analog-to-digital (A/D) inputs onthe microcontroller 1. The microcontroller software can then determinewhen the internal lithium battery is too hot to allow jumpstarting,adding safety to the design.

The main voltage regulator circuit 42 is designed to convert internallithium battery voltage to a regulated 3.3 volts that is utilized by themicrocontroller 1 as well as by other components of the booster devicefor internal operating power. Three lithium battery back chargeprotection diodes 28 (see FIG. 2 ) are in place to allow current to flowonly from the internal lithium battery pack 32 to the car battery 72,and not from the car battery to the internal lithium battery. In thisway, if the car electrical system is charging from its alternator, itcannot back-charge (and thereby damage) the internal lithium battery,providing another level of safety. The main power on switch 46 (FIG. 2A)is a combination that allows for double pole, double throw operation sothat with one push, the product can be turned on if it is in the offstate, or turned off if it is in the on state. This circuit also uses amicrocontroller output 47 to “keep alive” the power when it is activatedby the on switch. When the switch is pressed the microcontroller turnsthis output to a high logic level to keep power on when the switch isreleased. In this way, the microcontroller maintains control of when thepower is turned off when the on/off switch is activated again or whenthe lithium battery voltage is getting too low. The microcontrollersoftware also includes a timer that turns the power off after apredefined period of time, (such as, e.g. 8 hours) if not used.

The flashlight LED circuit 45 shown in FIG. 2B controls the operation offlashlight LEDs. Two outputs from the microcontroller 1 are dedicated totwo separate LEDs. Thus, the LEDs can be independentlysoftware-controlled for strobe and SOS patterns, providing yet anothersafety feature to the booster device. LED indicators provide thefeedback the operator needs to understand what is happening with theproduct. Four separate LEDs 61 (FIG. 2A) are controlled by correspondingindividual outputs of microcontroller 1 to provide indication of theremaining capacity of the internal lithium battery. These LEDs arecontrolled in a “fuel gauge” type format with 25%, 50%, 75% and 100%(red, red, yellow, green) capacity indications. An LED indicator 63(FIG. 2B) provides a visual warning to the user when the vehicle battery72 has been connected in reverse polarity. “Boost” and on/off LEDs 62provide visual indications when the booster device is provide jump-startpower, and when the booster device is turned on, respectively.

A USB output 56 circuit, as shown in FIG. 2C is included to provide aUSB output for charging portable electronic devices such as smartphonesfrom the internal lithium battery pack 32. Control circuit 57 from themicrocontroller 1 allows the USB Out 56 to be turned on and off bysoftware control to prevent the internal lithium battery getting too lowin capacity. The USB output is brought to the outside of the device on astandard USB connector 58, which includes the standard voltage dividerrequired for enabling charge to certain smartphones that require it. TheUSB charge circuit 52 allows the internal lithium battery pack 32 to becharged using a standard USB charger. This charge input uses a standardmicro-USB connector 48 allowing standard cables to be used. The 5Vpotential provided from standard USB chargers is up-converted to the12.4 VDC voltage required for charging the internal lithium battery packusing a DC-DC converter 49. The DC-DC converter 49 can be turned on andoff via circuit 53 by an output from the microcontroller 1.

In this way, the microcontroller software can turn the charge off if thebattery voltage is measured to be too high by the A/D input 22.Additional safety is provided for helping to eliminate overcharge to theinternal lithium battery using a lithium battery charge controller 50that provides charge balance to the internal lithium battery cells 51.

This controller also provides safety redundancy for eliminating overdischarge of the internal lithium battery.

FIG. 3 is a perspective view of a handheld device 300 in accordance withan exemplary embodiment of the invention. 301 is a power on switch. 302shows the LED “fuel gauge” indicators 61. 303 shows a 12 volt outputport connectable to a cable device 400, described further below. 304shows a flashlight control switch for activating flashlight LEDs 45. 305is a USB input port for charging the internal lithium battery, and 306is a USB output port for providing charge from the lithium battery toother portable devices such as smartphones, tablets, music players, etc.307 is a “boost on” indicator showing that power is being provided tothe 12V output port. 308 is a “reverse” indicator showing that thevehicle battery is improperly connected with respect to polarity. 309 isa “power on” indicator showing that the device is powered up foroperation.

FIG. 4 shows a jumper cable device 400 specifically designed for usewith the handheld device 300. Device 400 has a plug 401 configured toplug into 12 volt output port 303 of the handheld device 300. A pair ofcables 402 a and 402 b are integrated with the plug 401, and arerespectively connected to battery terminal clamps 403 a and 403 b viaring terminals 404 a and 404 b. The port 303 and plug 401 may bedimensioned so that the plug 401 will only fit into the port 303 in aspecific orientation, thus ensuring that clamp 403 a will correspond topositive polarity, and clamp 403 b will correspond to negative polarity,as indicated thereon. Additionally, the ring terminals 404 a and 404 bmay be disconnected from the clamps and connected directly to theterminals of a vehicle battery. This feature may be useful, for example,to permanently attach the cables 302 a-302 b to the battery of avehicle. In the event that the battery voltage becomes depleted, thehandheld booster device 300 could be properly connected to the batteryvery simply by plugging in the plug 401 to the port 303.

Battery Cell Equalization

A battery cell equalization circuit 110 is shown in FIG. 1 . The batterycell equalization circuit 110 comprises a Li-ion battery 112 havingthree (3) cells having a nominal battery rating of 12V, a battery cellequalization circuit 114 having three (3) 17 individual battery cellequalization circuits, and an enable/disable control circuit 116. Eachcell has its own independent battery cell equalization circuit, whichare essentially identical.

The battery cells are “equalized” using the principle that if any cellvoltage exceeds a certain pre-determined upper voltage threshold, itwill be discharged through its own load resistor (R5, R15, and R25),until it reaches a certain pre-determined level below that threshold oruntil the battery charging process is terminated.

Bleeding the charge of a cell through its load resistor may not alwaysresult in the net discharge of that cell. For example, if the(externally supplied) charging current through the Li-ion battery 112,which is the same through each cell, is higher than the discharge orbleed current of that cell, it will slow down the effective chargingrate of that cell while charging the lower voltage cells at a higherrate allowing them to catch up to the highest voltage cell.

The battery cell equalization circuit 110 is enabled or disabled using asingle control signal, which may be generated after evaluating useraffected settings or various operational conditions within the jumpstarter. Disabling the equalization circuit during active cell dischargestops the discharge of the cell(s). Enabling the equalization circuitmay or may not cause the cell(s) to be discharged, as that decisiondepends on the cell voltages.

Operation

Enabling the equalization circuit involves turning ON the MOSFETswitches 02, 04, 06, electrically connecting the voltage dividerresistors (R3, R4), (R13, R14) and (R23, R24) that scale down theindividual cell voltages and feed them to the non-inverting inputs oftheir respective comparators, allowing them to sense the individual cellvoltages. Disabling the equalization circuit turns OFF MOSFET switches02, 04, 06, disconnecting the resistors (R3, R4), (R 13, R 14) and (R23,R24) and preventing the cell voltages reaching the comparators'non-inverting inputs. That essentially presents zero voltage to thecomparators' non-inverting inputs, causing their output voltages to bezero, which prevents the load resistors R5, R15, R25 from beingconnected across the cells.

Semiconductor voltage references DZ_1, DZ_2, DZ_3 in series with biasingresistors R7, R17, R27, provide a reference voltage signal to theinverting input of comparators U1, U2, U3, respectively. The resistordivider R3, R4 (or R13, R14 or R23, R24) values are chosen such thescaled cell voltage equals the reference voltage when the cell voltagereaches the upper voltage threshold at which the discharge process needsto be started. If any scaled cell voltage being fed to the non-invertinginput of its respective comparator exceeds the corresponding referencevoltage present at the inverting input, then the comparator's outputvoltage will be high, exceeding the gate-source threshold voltage of theenhancement mode MOSFET switch 01 (or 03, 05), causing it to turn ON andconnecting load resistor R5 (or R15, R25) across the correspondingbattery cell.

Resistor R8 (or R18, R28) lies in parallel with R4 (or R14, R24) andallows fine tuning of the voltage division, allowing the use of cheaper,commonly available mass produced resistors, instead of a single specificnon-standard value. Further consideration in choosing the value of thevoltage divider resistors is to minimize the current drawn by theseresistors to avoid draining the battery cells, while at the same timekeeping their value small enough to allow enough current through thesevoltage divider resistors that is significantly greater than thecomparators' input bias current, so as to effectively not load thevoltage divider.

R1, R2 (R11, R12 or R21, R22) control the “hysteresis” band thatdetermines the lower cell voltage level to which the cell(s) needs to bedischarged, once the discharge process has been started.

Li-ion battery 112 can store a significant amount of energy, which cancause high current in the cells, if their terminals get short-circuitedun-intentionally, resulting in excessive heat generation and damage tothe jump starter unit or other undesired catastrophic consequences. Highvalued resistors R6, R16, R26 have been added between the output ofcomparator U1 (or U2, U3) and the switches QI, 03, 05 to limit theamount of current through each cell to a safe value, in the case whensomehow the output of U1 (or U2, U3) gets clamped to its cell voltageand the gate-source terminals of 01 (or 03, 05) get short-circuited.

The gate-source threshold voltage of MOSFETs 01, 03, 05 has been chosento be a minimum of 1.2V, as opposed to a few tenths of a volt, in orderto prevent their spurious turning ON due to stray voltages presentbetween their gate-source terminals. The comparators and voltagereferences used are of the “nano power” category to not drain thebattery cells significantly over time, thus maintaining its jumpstarting capacity.

Capacitors C1, C2, C3 are kept to allow stable operation of the voltagereferences DZ_1, DZ_2, DZ_3.

Enable/Disable Control Circuit Operation

Turning ON enhancement mode MOSFET switches 02, 04, 06 enables thebattery cell equalization circuit 110. Turning them OFF, disables thebattery cell equalization circuit 110. The switches 02, 04, 06 areturned ON simultaneously by applying a nominal 12V control voltagesignal between the terminals marked “Control+”, “Control −”. They aresimultaneously turned OFF by applying a nominal zero volt controlsignal. In this implementation, the control voltage needed to be greaterthan or equal to the nominal voltage of the battery whose cells arebeing equalized. The nominal 12V control voltage level was chosen due toits availability within, for example, a hand-held jump starter unit, asit is readily obtained via the external charge port or from the Li-ionbattery 112 itself.

Placement of the voltage divider resistor R3 (or R13, R23) on the drain(terminal 3) side of MOSFET switches 02 (04 or 06), instead of on thesource (terminal 2) side, is critical to the proper operation of theenable/disable circuit 116. If it is desired to keep 02 (04, 06) turnedON, it is essential to maintain its gate-source voltage at a levelhigher than its gate-source threshold voltage. When 02 (04, 06) getsturned on, the voltage drop across R3 (R13, R23) causes its sourceterminal to be pulled below its corresponding positive cell terminalpotential, enabling a gate to source voltage at a level higher than itschosen gate-source threshold voltage. To allow a larger voltage dropacross R3 (R13, R23), its value is kept much larger than R4 (R14, R24),such that it would allow a standard valued, readily available voltagereference DZ_1 (DZ_2, DZ_3) to be chosen.

The gate-source threshold voltage of MOSFETs 02, 04, 06 has been chosento be a minimum of 1.1V, as opposed to a few tenths of a volt, in orderto prevent their spurious turning ON due to stray voltages presentbetween their gate-source terminals. This in turn imposes a highervoltage requirement across the gate-source voltage of 02, 04, 06 inorder to turn them ON and keep them in that state. It can be seen thatif R3 were kept on the source (terminal 2) side of 02, then the sourceterminal of 02 would be pulled to the nominal 12V battery potential assoon as 02 were turned ON with a 12V control signal. However, this wouldresult in a zero voltage applied between the gate-source of 02,immediately turning it back OFF.

The values of R10, R30, R32 have been chosen to allow an equitabledistribution of the applied voltages between the gate-source terminalsof 02, 04, 06 when the 12V control voltage is present. R10, R32 are keptmuch smaller than R32 to allow similar amounts of current to reach thegates of 02, 04, 06. Large valued resistors R9, R19 act as another layerof safety by further introducing electrical resistance between theindividual battery cells 112 as well as between the battery and thecontrol voltage source by limiting fault current in case of shortcircuits across multiple components of the circuit. Value R32 needs tobe kept large enough so that most of the control voltage drops acrossit, in case the control voltage source has significant resistance inseries with it.

Example #1

The battery cell equalization circuit 110 can be applied or installedinto the battery jump start boost device disclosed in U.S. Pat. No.9,007,015, which is incorporated herein by reference.

The invention having been thus described, it will be apparent to thoseskilled in the art that the same may be varied in many ways withoutdeparting from the spirit or scope of the invention. Any and all suchvariations are intended to be encompassed within the scope of thefollowing claims.

It is claimed:
 1. A hand held, portable jump starter device, comprising:a housing having a multi-cell rechargeable battery including at leastthree battery cells connected in series, a USB input port for receivinga charging current from an external source to recharge the multi-cellrechargeable battery, and an output port for providing jump startingcurrent to an external vehicle; a USB charge circuit connected to theUSB input port, including a DC-to-DC converter circuit for upconvertingan input voltage on the USB input port to a higher charging voltage forrecharging the multi-cell rechargeable battery; a pair of seriesconnected transistor devices coupled between the USB charge circuit andthe multi-cell rechargeable battery for controlling current flow intoand out of the multi-cell rechargeable battery; a control circuit fordetecting the voltage of the multi-cell rechargeable battery andconfigured to turn off the USB charge circuit to prevent over chargingof the multi-cell rechargeable battery if the detected voltage exceeds athreshold value; a battery charge controller coupled to the multi-cellrechargeable battery and the pair of series connected transistor devicesand configured to prevent over discharging of the multi-cellrechargeable battery; and a battery cell equalization circuit connectedto the a multi-cell rechargeable battery, the battery cell equalizationcircuit comprising: a plurality of individual battery cell equalizationcircuits, each provided for one of the at least three battery cells; anda plurality of load resistors, each provided for one of the at leastthree battery cells, wherein each of the plurality of individual batterycell equalization circuits is configured to discharge a particularbattery cell by its particular load resistor upon the particular batterycell reaching a cell voltage exceeding a pre-determined upper voltagethreshold until the particular battery cell reaches a pre-determinedlower voltage level below the upper voltage threshold, and wherein theplurality of individual battery cell equalization circuits areconfigured to charge lower voltage individual battery cells at a higherrate allowing lower voltage individual battery cells to catch up involtage to an individual battery cell having a highest voltage.
 2. Thehand held, portable jump starter device of claim 1, further comprising:a power switch coupled between the multi-cell rechargeable battery andthe output port, the power switch allowing jump starter current to flowfrom the multi-cell battery to the output port when activated.
 3. Thehand held, portable jump starter device of claim 2, further comprising:a cable device having positive and negative cable clamps coupled to asingle plug that connects to the output port in a single orientation. 4.The hand held, portable jump starter device of claim 3, where the singleplug of the cable device has a substantially uniform width.
 5. The handheld, portable jump starter device of claim 1, further comprising: abattery measurement circuit coupled between the multi-cell battery andan analog-to-digital input of the control circuit.
 6. The hand held,portable jump starter device of claim 2, wherein the control circuit iscoupled to the power switch and provide a control signal for activatingthe power switch to allow jump starter current to flow from themulti-cell battery to the output port.
 7. The hand held, portable jumpstarter device of claim 6, further comprising a vehicle battery presencesensor coupled to the output port for detecting the presence of avehicle battery and for providing a detection signal to the controlcircuit.
 8. The hand held, portable jump starter device of claim 7,wherein the control circuit responds to the detection signal andactivates the power switch when a vehicle battery is detected at theoutput port.
 9. The hand held, portable jump starter device of claim 1,further comprising a USB output port coupled to the multi-cellrechargeable battery through a DC-to-DC converter for downconverting thevoltage of the multi-cell battery to a lower voltage output on the USBoutput port.
 10. The hand held, portable jump starter device of claim 9,wherein the control circuit is configured to disable the USB output portif the voltage of the multi-cell battery drops below a threshold value.11. The hand held, portable jump starter device of claim 1, wherein thebattery cell equalization circuit is configured to be enabled ordisabled using a single control signal.
 12. The hand held, portable jumpstarter device of claim 11, wherein disabling the battery cellequalization circuit during active battery cell discharge stops thedischarge of the battery cells.
 13. The hand held, portable jump starterdevice of claim 11, wherein the battery cell equalization circuitcomprises MOSFET switches and voltage divider resistors, and whereinenabling the battery cell equalization circuit involves turning on theMOSFET switches electrically connecting the voltage divider resistorsthat scale down individual cell voltage of the battery cells and feedthem to non-inverting inputs of respective comparators, allowing them tosense the individual cell voltages.
 14. The hand held, portable jumpstarter device of claim 12, wherein disabling the battery cellequalization circuit turns off the MOSFET switches disconnecting theresistors and preventing cell voltages reaching the comparators'non-inverting signals and presenting zero voltage to the comparator'snon-inverting inputs, causing their output voltages to be zero, whichprevents the load resistors from being connected across the cells.
 15. Ahand held, portable jump starter device, comprising: a housing having amulti-cell rechargeable battery including at least three battery cellsconnected in series, a USB input port for receiving a charging currentfrom an external source to recharge the multi-cell rechargeable battery,and an output port for providing jump starting current to an externalvehicle; a USB charge circuit connected to the USB input port, includinga DC-to-DC converter circuit for upconverting an input voltage on theUSB input port to a higher charging voltage for recharging themulti-cell rechargeable battery; a pair of series connected transistordevices coupled between the USB charge circuit and the multi-cellrechargeable battery for controlling current flow into and out of themulti-cell rechargeable battery; a control circuit for detecting thevoltage of the multi-cell rechargeable battery and configured to turnoff the USB charge circuit to prevent over charging of the multi-cellrechargeable battery if the detected voltage exceeds a threshold value;a battery charge controller coupled to the multi-cell rechargeablebattery and the pair of series connected transistor devices andconfigured to prevent over discharging of the multi-cell rechargeablebattery; and a battery cell equalization circuit connected to themulti-cell rechargeable battery in parallel with the battery chargecontroller, wherein the battery cell equalization circuit includes anindividual battery cell equalization circuit for each of the at leastthree battery cells, and wherein each of the individual battery cellequalization circuits is configured to discharge a particular batterycell upon the particular battery cell reaching a cell voltage exceedinga pre-determined upper voltage threshold until the particular batterycell reaches a pre-determined lower voltage level below the uppervoltage threshold; wherein the individual battery cell equalizationcircuits are configured to charge lower voltage individual battery cellsat a higher rate allowing lower voltage individual battery cells tocatch up in voltage to an individual battery cell having a highestvoltage.
 16. The hand held, portable jump starter device of claim 15,further comprising: a power switch coupled between the multi-cellrechargeable battery and the output port, the power switch allowing jumpstarter current to flow from the multi-cell battery to the output portwhen activated.
 17. The hand held, portable jump starter device of claim16, further comprising: a cable device having positive and negativecable clamps coupled to a single plug that connects to the output portin a single orientation.
 18. The hand held, portable jump starter deviceof claim 17, where the single plug of the cable device has asubstantially uniform width.
 19. The hand held, portable jump starterdevice of claim 15, further comprising: a battery measurement circuitcoupled between the multi-cell battery and an analog-to-digital input ofthe control circuit.
 20. The hand held, portable jump starter device ofclaim 16, wherein the control circuit is coupled to the power switch andprovide a control signal for activating the power switch to allow jumpstarter current to flow from the multi-cell battery to the output port.21. The hand held, portable jump starter device of claim 20, furthercomprising a vehicle battery presence sensor coupled to the output portfor detecting the presence of a vehicle battery and for providing adetection signal to the control circuit.
 22. The hand held, portablejump starter device of claim 21, wherein the control circuit responds tothe detection signal and activates the power switch when a vehiclebattery is detected at the output port.
 23. The hand held, portable jumpstarter device of claim 15, further comprising a USB output port coupledto the multi-cell battery through a DC-to-DC converter fordownconverting the voltage of the multi-cell battery to a lower voltageoutput on the USB output port.
 24. The hand held, portable jump starterdevice of claim 23, wherein the control circuit is configured to disablethe USB output port if the voltage of the multi-cell battery drops belowa threshold value.
 25. The hand held, portable jump starter device ofclaim 23, wherein the battery cell equalization circuit is configured tobe enabled or disabled using a single control signal.
 26. The hand held,portable jump starter device of claim 25, wherein disabling the batterycell equalization circuit during active battery cell discharge stops thedischarge of the battery cells.
 27. The hand held, portable jump starterdevice of claim 25, wherein the battery cell equalization circuitcomprises MOSFET switches and voltage divider resistors, and whereinenabling the battery cell equalization circuit involves turning on theMOSFET switches electrically connecting the voltage divider resistorsthat scale down individual cell voltage of the battery cells and feedthem to non-inverting inputs of respective comparators, allowing them tosense the individual cell voltages.
 28. The hand held, portable jumpstarter device of claim 27, wherein disabling the battery cellequalization circuit turns off the MOSFET switches disconnecting theresistors and preventing cell voltages reaching the comparators'non-inverting signals and presenting zero voltage to the comparator'snon-inverting inputs, causing their output voltages to be zero, whichprevents the load resistors from being connected across the cells.